IN VIVO DOSIMETRY USING GAFCHROMIC EBT3 FILM IN TOTAL BODY IRRADIATION

Abstract

The purpose of this study is to measure the dose in the phantom and patients during total body irradiation by EBT3 film. The techniques of TBI were two lateral parallel opposing fields at extended SAD of 500 cm for 200 cGy/fraction, 2 fractions per day in 3 days and aimed 1200 cGy at the head and legs. The remainder dose of less than 1200 cGy in chest and abdomen parts were added with AP/PA fields by 3D-CRT with lung and kidney shielded by MLC in the 7th fraction. The dose measurement was performed in 1 plan of patient in lateral fields for 6 fractions and 4 plans in phantom and 5 plans in patient in AP/PA fields using 3D-CRT in Eclipse TPS. The films were placed in phantom and patient of shoulder, armpit, chest, umbilicus, abdomen, groin and thigh. For lateral fields, the average dose difference was 0.4±2.7%. For 3D-CRT in phantom, the average dose difference was -2.9±1.2%. The average dose difference in lung and kidney were -3.3±3.4% and -3.0±6.0%, respectively. For patient, the average dose difference was -0.8±1.6%. The results were agreed with Petra M.H et al who reported 0.7±2.1% and 0.5±4.7% differences between measured and calculated dose in phantom and patient, respectively. The performance of EBT3 film for TBI dosimetry shows reliable for calculation of patient dose with less than ±5% of uncertainties.